Think of the bear crawl like a traveling plank. You have to maintain the same rigid, neutral torso you would while in a plank position, but now you're moving forward, backward, and side-to-side. As your arms and legs move, the more than two dozen muscles in your core must resist the urge to rotate and flex, says De Wispelaere. If you do this often enough, you'll soon notice more stability, strength, and power in everything you do—plus a more chiseled middle.

Ready to try it for yourself? Start with this simple—but core-crushing—bear crawl circuit. Travel 10 yards to your right and then 10 yards to your left. Rest and repeat. Watch the video below to see how to perform the move with perfect form.